PHP - mysqli_fetch_assoc() expects

require '../phpmailer/PHPMailerAutoload.php';

include '../conexion.php';

$id = $_POST['id_del'];

$sql = mysqli_query($conexion,"UPDATE pqrsf SET id_estado_pqrsf = '4' WHERE id_estado_pqrsf = '3' and id_pqrsf = '$id'");

$result = mysqli_query($conexion,"SELECT u.email_usuario_pqrsf

          FROM usuario_pqrsf u 

          INNER JOIN pqrsf p 

          ON u.id_usuario_pqrsf = p.id_usuario_pqrsf 

          WHERE p.id_pqrsf = '$id'");

$row = mysqli_fetch_assoc($result);

$mail = new PHPMailer();

$mail->isSMTP();

$mail->Host = 'mail.unic.edu.co';

$mail->SMTPAuth = true;

$mail->CharSet = 'UTF-8';

$mail->Username = 'ponder@unic.edu.co';

$mail->Password = '!@sasDs}0uY';

$mail->SMTPSecure = 'ssl';

$mail->Port = 465;

$mail->setFrom('ponder@unic.edu.co');

$mail->addAddress($row['email_usuario_pqrsf']);

$mail->IsHTML(true);

$mail->Subject = 'Respuesta PQRSF';

$mail->Body = 'prueba';

if($mail->send() == false){

echo "No se pudo enviar ";

echo "Error del PHPMailer ". $mail->ErrorInfo;

}else{

echo "se envio";

}